How should I ground my multiplus and inversion transformer on my aluminum boat

Hi,
I have an aluminium sailboat. Right now nothing electrical is connected to the hull.
I have a multiplus and an isolation transformer.

I have grounded the multiplus enclosure to the battery negative with a big cable (similar to the actual negative cable)

I wonder what I should do with the AC grounding. Should I connect the AC earth wire to the hull? Or the isolation transformer enclosure? Or nothing at all?

Thank you !